The present invention relates to a test system for analyzing body fluids, in particular blood, of the type comprising a test element tape carrying a plurality of test elements that is preferably wound in a tape cassette, a tape deflector for the test element tape for the directed application of body fluid, and a light source as well as a detector to optically analyze test elements to which body fluid has been applied.
Portable devices operating as minilaboratories, which can also be used by laymen to carry out the required steps in a simple and rapid manner are known for self-monitoring blood glucose by diabetics. In order to replace conventional test strips, it is proposed in WO 2004/047642 that instead of individual test strips, a wound test tape should be used on which a plurality of test fields provided with a suitable test chemistry are arranged consecutively. The body fluid is applied to a test field that is moved into an active position by advancing the tape over a tip and analyzed. Details on blood collection as well as on the known test media and detection systems especially for blood glucose are disclosed in this document to which reference is herewith made and the contents of which are incorporated by reference into this application. This document also shows that a transparent tip can be used to directly couple the instrument optics. Constraints that have to be observed in this case are that the total height of the deflector tip and its opening angle should be as small as possible but it should still be possible to optically analyze the test field for example on the basis of a reflectance measurement or a fluorescence measurement.